The present invention relates to an aeration/flotation reactor which is particularly useful in the treatment of biomass-containing liquids. In general terms, the reactor has a foam tube equipped, at its top, with a collecting vessel and at its bottom with an inlet chamber for the entry of liquid and gas in the form of fine bubbles.
Aeration and flotation of biomass-containing liquids can play an important role in various areas of biotechnology. A specific example of such a role relates to the treatment of waste water from seawater aquaria. Protein-containing material is constantly added, as feed, to the water of such aquaria, and can collect. Over a relatively prolonged period, this material is then degraded by microorganisms, leading to the accumulation of nitrate, which is especially harmful to sensitive sea animals.
One way of keeping the nitrate content low is via the denitrifying treatment of the water in a rotating fixed-bed reactor, as described in the present inventor's German patent application No. P 3,608,466, filed Mar. 14, 1986. But water denitrified in such a reactor cannot be fed back into an aquarium without an aftertreatment because it (i) contains no life-supporting oxygen; (ii) is permeated with water-turbidifying biomass; (iii) has a redox potential of -220 mV, compared to a desired value in the range of between +200 and +230 mV; and (iv) possibly contains nitrite, which is extremely toxic even at low concentrations (.gtoreq.1 mg/l).